Substituted pyrazolylthioacetic acids and esters thereof



United States Patent 3,282,954 SUBSTKTUTED PYRAZOLYLTHIOACETIC AClDS AND ESTERS THEREOF Robert G. Stein and Hollis G. Schoepke, Waukegan, Ill.,

assignors to Abbott Laboratories, Chicago, 11]., a corporation of Illinois No Drawing. Filed Aug. 7, 1964, Ser. No. 388,270 18 Claims. (Cl. 260310) This invention relates to novel compounds of the forand a method for their preparation. In these and succeeding formulas, R, R and R represent hydrogen, loweralkyl with from 1 to 4 carbon atoms, phenyl, halopheny-l, loweralkylphenyl or .loweralkoxyphenyl. These compounds are useful as trichomonac'ides and will completely inhibit the growth of T richomonns vaginalis at concentrations of 100 parts per million of water when employed as aqueous solutions or suspensions.

The pyrazolylthioacetic acids of Formula A are readily prepared by the reaction of equimolecular proportions of an R -substituted mercaptoacetic acid and a 1,3-substituted-4-nitro-5-chloropyrazole of the formula in the presence of an HCl acceptor such as sodium bicarbonate. The react-ion is conveniently carried out by adding an alcoholic solution of the pyrazole to an aqueous solution of the mercapto acetic acid and sodium bicarbonate at room temperature and thereafter refluxing the resulting mixture for a few hours to complete the reaction. The mixture is then poured over ice and acidified to precipitate the desired pyrazolylthioacetic acid which is recrystallized from a suitable organic solvent such as a benzene-petroleum ether mixture.

The corresponding ethyl esters of Formula B are prepared by refluxing the pyrazolylt-hioacetic acids in ethanol in the presence of a catalytic amount of concentrated sulfuric acid. When the esterification is complete, the solution is concentrated, washed successively with aqueous alkali and water and recrystallized or fractionally distilled to obtain the desired ester as a crystalline solid or mobile liquid.

The following examples set forth the best mode of performing the invention but should not be construed as the sole embodiments thereof.

Example I.-a-(1-is0propyl-3-methyl-4-nitr0-5-pyraz0lylthio-acetic acid A solution of 28.4 grams (0.14 mole) of l-isopr-opyl- 3-methyl-4-nitro-5-chloropy azole in 200 ml. of ethyl alcohol was added dropwise to a solution of 12.9 grams (0.14 mole) of mercapto acetic acid and 23.5 grams (0.28 mole) of sodium bicarbonate in 250 ml. of water at room temperature. The resulting mixture was refluxed for 5 hours and then poured into 800 ml. of ice water. After acidifying with concentrated hydrochloric acid, the solid which precipitated was separated by filtration, washed with water and recrystallized from benzene-petroleum ether to obtain the desired product which melted at 142 C.

Examples 21 0 By reacting the appropriate R -substituted mercapto acetic acid with a 1,3-substituted-5-chloro-4-nitro pyrazole of Formula C in the same manner as that described in Example 1, the following a-(5-pyrazolylthio)acetic acids are obtained wherein R, R and R of Formula A are as shown in the table below.

Example No. R R R2 M.P. in C.

2 CH3 CH3 H 143 3 CH3 CH3 CH 155 4 n-Propyl CH3. H 128 5 n-Butyl CH H 123 6 Phenyl- CH H 145 7 01% Isopropyl.-. H 8 H CH': H 195 Q Ethyl CH H 10 CH; n Propy1 H 137 Example 1 1 .--Ethyl a (1 -is0pr0pyl-3-methyl-4-nitr0-5- pyrazoly lthio) acetate CH C C-N 02 N (H'J-SCHQCOOC2H5 Examples 12-18 In a manner similar to that described in Example 11 except that the reaction mixture was fractionalwly distilled instead of recrystallized, other R, R -substituted-4- nitro-S-pyrazolylmercaptoacetic acids of Formula A were refluxed with ethyl alcohol to obtain the corresponding ethyl esters of Formula B wherein R, R and R were as indicated in the following table:

Example No. R R1 R2 B.P. in C.

CH: CH1 H 187 at 4 111m. GHQ CH1 CH3 172 at 2 mm. n-Propyl.- CH3 157 at 0.4 mm. CH t-Butyl H 152 at 0.8 mm. EthyL CH1 at 1 mm. CH3 nPropyl. CH 159 at 0.5 mm. CH3 do H at 0.7 mm.

By employing the procedure set forth in the foregoing examples, other compounds corresponding to Formula A or B can be prepared wherein R, R and R represent such radicals as p-chlorophenyl, o-bromophenyl, p-methylphenyl, o-butylphenyl, p-rnethoxyphenyl or o-isopropoxyphenyl and the like.

The 1,3-substituted-4-nitro-S-chloropyrazoles of Formula C employed as one of the starting materials in the 3 present invention are readily prepared by known methods. Thus, a pyrazolinone of the formula Rr-O CH ll II N O=O is reacted with POCl at a temperature of 100-150 C. to form the corresponding S-chloropyrazole of the formula Ri--GH l I iCl which is then nitrated with fuming nitric acid at from 0 to 25 C. The melting and boiling points of typical pyrazoles of Formula C are shown in the following table.

We claim: 1. A compound selected from the group consisting of compounds of the Formula A R OCNOz N (E-S-CH-COOCH and compounds of the Formula B R1C C-NO:

I I (i-s-OH-(J 0 002115 wherein R, R and R are independently selected from the group consisting of hydrogen, loweralkyl, phenyl, halophenyl, lower-alkylphenyl and loweralkoxyphenyl.

2. A compound of Formula A as claimed in claim 1 in which R is isopropyl, R is methyl and R is hydrogen. 3. A compound of Formula A as claimed in claim 1 in which R and R are methyl and R is hydrogen.

4. A compound of Formula A as claimed in claim 1 in which R, R and R are all methyl.

5. A compound of Formula A as claimed in claim 1 in which R is n-propyl', R is methyl and R is hydrogen. 6. A compound of Formula A as claimed in claim 1 in which R --is n-butyl, R is methyl and R is hydrogen. 7. A compound of Formula A as claimed in claim 1 in which R is phenyl, R is methyl and R is hydrogen. 8. A compound of Formula A as claimed in claim 1 in which R is methyl, R is isopropyl and R is hydrogen. 9. A compound of Formula A as claimed in claim 1 in which R and R are hydrogen and R is methyl.

10. A compound of Formula A as claimed in claim 1 in which R is ethyl, R is methyl and R is hydrogen.

11. A compound of Formula B as claimed in claim 1 in which R is isopropyl, R is methyl and R is hydrogen. 12. A compound of Formula B as claimed in claim 1 in which R and R are methyl and R is hydrogen,

13. A compound of Formula B as claimed in claim 1 in which R, R and R are all methyl.

14. A compound of Formula B as claimed in claim 1 in which R is n-propyl, R is methyl and R is hydrogen. 15. A compound of Formula B as claimed in claim 1 in which R is methyl, R is t-butyl and R is hydrogen. 16. A compound of Formula B as claimed in claim 1 in which R is ethyl, R is methyl [and R is hydrogen. 17. A compound of Formula B as claimed in claim 1 in which R is methyl, R is n-propyl and R is hydrogen. 18. A compound of Formula B as claimed in claim 1 in which R and R are methyl and R is n-propyl.

References Cited by the Examiner UNITED STATES PATENTS 2,615,895 10/ 1952 Archer 260294.8 2,977,368 3/1961 Druey et a1. 260-2948 OTHER REFERENCES Conant et al.: The Chemistry of Organic Compounds, 3d ed., page 91, New York, Macmillan, 1947.

Fisher et al.: Canadian Journal of Chemistry, vol. 39, pages 785-88 (1961).

Noller: Chemistry of Organic Compounds, 2d ed., pages 152 and 168, Philadelphia, Saunders, 1958.

WALTER A. MODANCE, Primary Examiner. N. TROUSOF, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,282,954 November 1, 1966 Robert G Stein et a1.

It is hereby certified that er patent requiring correction and th read as corrected below.

ror appears in the above numbered at the said Letters Patent should Column 3, lines 36 to 41,

the formula should appear as shown below instead of as in th e patent:

R C-C NO Signed and sealed this 5th day of September 1967.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS OF THE FORMULA A 1-R,3-R1,4-NO2,5-(CH3-OOC-CH(-R2)-S-)PYRAZOLE AND COMPOUNDS OF THE FORMULA B 1-R,3-R1,4-NO2,5-(C2H5-OOC-CH(-R2)-S-)PYRAZOLE WHEREIN R, R1 AND R2 ARE INDEPENDENTLY SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, LOWERALKYL, PHENYL, HALOPHENYL, LOWERALKYLPHENYL AND LOWERALKOXYPHENYL. 